A method of measuring quality of communication by communicating between a server such as an automatic voice response apparatus and a communication terminal apparatus such as a mobile telephone via a mobile communication network at a predetermined given measurement time is conventionally known.
As an index value of communication quality, for example, a MOS (Mean Opinion Scores) value indicating voice quality in a voice communication is also known, which is standardized in Non-Patent Literature 1, Non-Patent Literature 2 and the like. This MOS value is a computed value corresponding to an average value of scores on five-grade evaluation by a large number of persons based on comparison results between a voice to be evaluated and a voice of a reference sound source. In Non-Patent Literature 1 and Non-Patent Literature 2, international standard methods of mechanically realizing the foregoing computation of MOS values are described.